No description available.

No description available.

The reaction of Mg(NPh2)2 with LiNR2 (R= SiMe3, NiPr, NiBu) generated the same product, [Mg(NPh2)3(THF)][Li(THF)4] which was identified by 1H-NMR and X-ray crystallography. The magnesium-lithium mixed metal complex reacted with excess carbon dioxide in the ice bath to generate the tetralithium complex, Li4(O2CNPh2)4(THF)4 which was identified by 1H-NMR, 13C-NMR, IR, and X-ray crystallography.

Separation methods involving a mixture of metals typically include upfront processing that leads to one final product. To lower the waste and ultimately environmental burden, the potential to synthesize multiple functional products from a mixed metal precursor solution is explored. The initial precursor solutions contained varying ratios of gold and copper, gold and nickel, and finally a ternary solution of gold, copper, and nickel. The amount of gold was kept constant, while the amount of copper and/or nickel was sequentially increased. Two separate synthesis processes were tested, the traditional Turkevich method involving trisodium citrate and another chemical reduction method involving sodium borohydride. The particle size and chemical composition of the synthesized particles were characterized using TEM, DLS and ICP-OES. It was determined that gold nanoparticles still formed at a ratio of 1 to 2 gold to copper while using trisodium citrate or sodium borohydride as the reducing agent. The same limiting ratio was observed for the gold to nickel reactions in the presence of either trisodium citrate or sodium borohydride. The ternary mixture limit for gold nanoparticle formation was a molar ratio of 1 to 1 to 1 gold to copper to nickel. The repeatability and stability results for the optimized binary reaction conditions indicate that using sodium borohydride as the reducing agent consistently produces more stable particle suspensions. Quantifying the environmental impact using green chemistry metrics indicate the Turkevich reactions for the optimized reactions have the lower environmental factors.

A photolytic cell system suitable for the treatment of wastewater streams containing three pesticides, i) acephate, ii) glyphosate and iii) malathion is reported. The system is capable of destroying these three organic compounds, commonly present in wastewater streams originating from agrochemical industries in Malaysia, and can lead to complete mineralisation under the optimum conditions. The system is based on an advanced oxidation process and involves the production of hydroxyl free radicals in the presence of a UV source. The performance of the system, for the three pesticides, was optimised by investigating the effects of i) UV source, ii) pH of the solution, iii) initial concentration of the substrate, iv) addition of oxidants, v) hydrogen peroxide (H2O2) in the presence and absence of single and mixed metal ions. To monitor the degradation efficiency of the system, the residual concentrations of these organic compounds and metal ions were analysed using five analytical techniques i) total organic carbon (TOC), ii) high performance liquid chromatography (HPLC), iii) ion chromatography (IC), iv) UV/Visible spectroscopy (UV/Vis), and v) atomic absorption spectroscopy (AAS). The data show that the developed photolytic cell system is capable of achieving complete mineralisation of the three pesticides with the use of both 400 W and 600 W UV lamps. However, the 400W UV lamp was used, for economic reasons, to optimise the system for the remaining factors. Changes in the pH of aqueous solutions influenced the degradation efficiency and a complete degradation of the three pesticides was achieved at their self-pH values ranging from 5.0-5.5. The degradation of acephate increased and malathion decreased at their higher initial concentrations whereas no significant effect related to concentration was observed for glyphosate. Results show that the degradation followed a first order kinetics and the degradation rates were: malathion > acephate > glyphosate. The addition of 30 mg/L of H2O2 enhanced the degradation of the pesticides and after 5 hours irradiation these were 95.7%, 91.5% and 81.3% for malathion, acephate and glyphosate respectively. The presence of metal ions was observed to affect degradation (Table 1). With 5.0 mg/L of Fe(II) the degradation of all three pesticides increased, and in all cases acephate removal was improved. Removal of both malathion and glyphosate was negatively affected by copper, an effect that work with mixtures indicated was stronger than the positive effect of iron. The addition of H2O2, in the presence of single metal ions, increases the degradation. However, the addition of H2O2, in the presence of mixed metal ions, has no significant effect on the degradation of glyphosate and malathion. The effect of mixed metal ions on the three pesticides and the effect of Zn(II) ions on acephate and malathion are reported for the first time in this thesis. The developed photolytic cell system can be used for the treatment of wastewater streams originating from point sources, for example, agrochemical industries, under the optimum conditions. The synergistic combination of the developed system with the existing standard technologies is also proposed for the treatment of surface water at water treatment facilities in Malaysia. The application of the developed system can also be extended, with minimum modifications, for the treatment of wastewater streams originating from different manufacturing industries in Malaysia, for example, textile, paper/pulp, printing, coke, petroleum, paint, solvent, pharmaceuticals and wood-preserving chemicals. All these industries produce wastewater streams containing low concentrations of organic pollutants and heavy metal ions.

Lewis acids are widely used in the pharmaceutical industry, generally homogeneously, to perform reactions such as C-C or C=N bond formation and acetalisation. Typically, metal salts such as those of Ti, Fe and especially Sc are used, the last typically as the triflate. Metal organic frameworks (MOFs) containing such metals should act as heterogeneous, removable and reusable catalysts for similar reactions if they can be prepared in stable forms and with large, open pores and metal cation sites that can be rendered coordinatively unsaturated. Families of novel MOFs with different structure types and cations have therefore been prepared and their activity has been examined in carbonyl ene C-C bond forming reactions, Friedel-Crafts-Michael additions and in imine formation reactions. Their activities have been compared with those of the well-known HKUST-1(Cu), MIL-100(Fe) and MIL-101(Cr) solids examined as catalysts previously. In particular, divalent transition metal bisphosphonates and dicarboxylates with pore sizes from 10 – 20 Å and scandium carboxylates (MIL-68(Sc), MIL-88D(Sc), MIL-100(Sc), MIL-101(Sc)) have been tested. Synthetic procedures were optimised according to commercial constraints for the known MOFs STA-12(Ni) and MIL-100(Sc). While good activities are observed for Ni-based MOFs and in a number of the scandium-based solids, MIL-100(Sc) is by far the best Lewis acid catalyst for a range of reactions. In particular, MIL-100(Sc) is very active even when used without pre-dehydration, is readily recyclable with minor loss of activity and shows fully heterogeneous activity. It outperforms both MIL-100(Fe) and MIL-101(Cr), each commonly reported as versatile catalysts in the literature. Careful synthesis of bulky substrates shows that the activity is derived from reactions within the internal pore system. Furthermore, MIL-100(Sc) is able to perform tandem reactions - such as dehydration followed by carbonyl ene reaction - in which the Lewis acid sites catalyse two steps. The Lewis acidic sites of the excellent Lewis acid catalyst MIL-100(Sc) has been examined in detail by in situ IR using adsorption of CO and CD₃CN as probe molecules and compared with other MIL-100 materials. The work has been extended to the examination of MOFs containing two different metals, by substitutional approaches within the metal nodes (e.g. Sc-Al, Sc-Fe, Sc-Cr, Sc-Ni, Sc-Co within the trimeric M₃O(O₂C-)₆ nodes of MIL-100). In addition, series of Sc-Fe MIL-100 materials have been prepared that contain α-Fe₂O₃ nanoparticles in the pores of the structure. These composites show higher specific catalytic activity for Lewis acid catalysis than MIL-100(Sc), even though some scandium has been replaced with iron: the origin of this behaviour is discussed. MIL-100(Sc/Fe) has also been explored as a bifunctional catalyst in tandem Friedel-Crafts-oxidation reactions. MIL-100(Sc₆₀/Fe₄₀) was found to give exceptionally high conversions in the Friedel-Crafts-oxidation tandem reaction of 2-methyl indole and ethyl trifluoropyruvate to form a ketone, outperforming the many other materials tested and giving the best balance of the two different types of catalytic sites required to catalyse the reaction. MIL-100(Sc) has also been prepared containing 50% of mono-fluorinated trimesate ligands in the framework for the first time. This fluorinated MIL-100(Sc) has been post-synthetically modified by addition of a di-phenylphosphino group as confirmed by solid state NMR. This can act as a starting point for the future generation of MOF-supported metal phosphine catalysts.

Thesis (Ph. D. (Biochemistry)) -- University of Limpopo, 2004 / The NRF/Royal Society Initiative, and the University of the North Research Development & Administration

Traditional methods of synthesizing inorganic materials, such as hydrothermal, sol-gel, calcination and grinding steps, can typically require use of high temperatures, expensive precursors or use of solvents. Because of the energy-intensive nature or environmental impact these techniques, there is a push, especially from an industrial perspective, to move towards greener approaches. Mechanochemistry is a solvent-free alternative technique that can be used to synthesize a variety of materials under ambient conditions. Due to this, there is an increase in attention towards the use of this approach in both solid-state inorganic and organic chemistry. This dissertation reports the mechanochemical synthesis of a few inorganic materials without the need of using high temperatures or solvents. Additionally, examples are presented in which mechanochemistry is used in conjunction with a secondary technique. This mechanical activation of the precursors lead to a decrease in calcination temperature and reactions times, as well as alteration of properties or unique reaction products. The synthesis of kaolinite, vanadia nanostructures, and spinels were carried out in this fashion. Mechanical activation of the precursors allowed for reduced hydrothermal treatment times in case of both kaolinite and vanadia nanostructures and the spinels are calcined at lower temperature for shorter periods of time. In addition, we report alternative template agents than previously reported for the formation of vanadia nanotubes, and report the formation of nanorods. Choosing the appropriate amine template can alter the structure and size of the material. Isomorphously substituted mixed oxides, kaolinite and spinels (MgAl2O4 and ZnAl2O4) were synthesized through a mechanically assisted process. Kaolinites are treated hydrothermally iv for 1 week at 250 ºC to produce an X-ray pure crystalline material. The spinels undergo calcination as low as 500 ºC to produce a nanocrystalline material. Rare-earth metals and transition metals were used as the substitutional atom. The substituted kaolinites exhibit strong order along the c axis, but less ordering along the a and b axes. Trivalent chromium and trivalent rare-earth metals, such as La, Ce, Pr, Nd, Eu, Gd, Ho, and Er, are used to replace aluminum in the structure. Likewise, divalent and trivalent transition, such as Mn, Ni, Cu and Cr, are used as the substitutional atoms in MgAl2O4 and ZnAl2O4. Cathodoluminescence studies on the substituted Spinel structure show that Mn 2+ ions can occupy both the tetrahedral or octahedral holes to give a green and red emission, respectively. On the other hand, Cr3+ ions only occupy the octahedral holes to yield a red emission, similar to that in ruby. These isomorphously substituted materials may have potential applications in catalysis or glaze materials in ceramics. Oxidized graphite, an alternative to graphite oxide and graphene, can be synthesized rapidly by mechanochemical means. Grinding urea hydrogen peroxide adduct with graphite without the need of a solvent produces a product with an oxygen content of 5-15 wt%. The byproducts of this reaction are urea and water. This material is oxidized along the edges of the sheets, allowing it to be hydrophilic while retaining the conductivity. The material can suspend in water and processing allows for films of resistivities between 50 Ω cm-2 and 10 kΩ cm-2 . It was determined that the edges are fully oxidized to yield –COOH groups. This process offers a scalable, environmentally benign route to large quantities of oxidized graphite. An alternative method for the synthesis of nanostructured vanadia is reported. This process involves mechanical grinding of vanadium pentoxide, V2O5, with an amine template, v such as diphenylamine, theophylline, rhodamine 6G and rhodamine, prior to hydrothermal treatment. This allows for the synthesis of VOx nanotubes and nanorods dependent on which template is used. Diphenylamine, theophylline, and rhodamine B produce nanorods. Use of rhodamine 6G produces asymmetric VOx nanorods. In addition to the mixed metals oxides mentioned above, sodium and calcium tantalates are synthesized mechanically. This route does not require the need of elevated temperatures or expensive and hazardous materials. X-ray diffraction analysis of NaTaO3, Ca2Ta2O7, Ca4Ta2O9 and CaTa2O6 shows that these are the only phases detected after 4 h, 10 h, 27 h and 10 h of milling, respectively. During the synthesis of Ca2Ta2O7, an intermediate phase, Ca4Ta2O9, forms within 1 h, which reacts after 5 h to form the desired product. Reference Intensity Ratio analysis shows that the material synthesized mechanically is nanocrystalline Ca2Ta2O7. Nanocrystalline ZrSi2 can also be obtained through mechanochemical synthesis. This method allows for size control and results in crystallites ranging from 9 to 30 nm. Dilution with CaCl2 enables the size control process. A linear relationship exists between the concentration of CaCl2 and the crystallite size. Contrary to a typical self-propagating metathesis reaction, this process does not allow for self-propagation and requires continuous input of mechanical energy to continue. However, this method allows for non-passivated nanoparticles of ZrSi2, which can be incorporated into composites as a reinforcement material for several applications. Hard and ultra-compressible borides, such as ReB2 and OsB2, can be synthesized mechanically. The traditional synthesis of ReB2 requires excess boron due to treatment at high temperatures. This can lead to amorphous boron aggregating at the grain boundaries, which in vi turn, this would degrade the properties of the material. The mechanochemical approach requires mechanical treatment of Re and B powders in stoichiometric quantities for 80 h. Mechanical synthesis of OsB2 powders requires a 1:3 ratio of Os and B powders. After 12 h of milling time, h-OsB2 begins to form, and is the major phase present after 18 h. The lattice parameters corresponding to the hexagonal OsB2 were determined to be a = b = 2.9047 Å, c = 7.4500 Å, α = β = 90º, γ = 120º. Treatment of the OsB2 powder at 1050 ºC under vacuum for 6 days did not induce a phase change, suggesting the hexagonal phase is very stable. Mechanocatalysis of the depolymerization of cellulose and hydrogenation of olefins over BN are reported as well. Heterogeneous catalysis is difficult to apply to solids, such as cellulose. However, mechanical grinding of kaolin and cellulose allows for the catalysis to occur in the solid state. This process allows for a variety of different biomasses to be used as feedstock without inhibition. Kaolinite was found to be the best acid catalyst due to high surface acidity and its layered structure, allowing for up to 84% conversion of the cellulose to water-soluble compounds. This process allows for reduction of waste, insensitivity of feedstock, multiple product pathways and scalability. Hydrogenation reactions are carried out using transition-metals catalysts. These metals have desirable catalytic properties not seen in main group elements, but there is growing concern over their use. A metal-free heterogeneous hydrogenation catalyst based on frustrated Lewis pairs would significantly reduce the health, environmental, and economic concerns associated with these metal-based catalysts. We report the first metal-free heterogeneous hydrogenation catalyst. Hydrogenation of trans-cinnamic acid is carried out over defect-laden h-BN. The vii reactor we use is designed to maximize the defects produced in BN sheets. The introduction of defects in BN creates frustrated Lewis pairs. DFT calculations show that the carbon double bond is weakened over boron substitution for nitrogen sites, vacancies of both boron and nitrogen, and Stone-Wales defects. A new method for crystalline germanium deposition occurring at lower temperatures (210-260 ºC) is reported. This method involves mechanical treatment of the precursors to reduce the particle size. A ground mixture of Ge and CuI are heated under vacuum to synthesize GeI2. In situ disproportionation of this compound at 210 ºC allows for the deposition of polycrystalline Ge films onto a both glass and polymer substrates. The rate of deposition is found to be 25 ng min-1 . The byproducts of this process are GeI2, GeI4 and Cu3Ge, which are valuable precursors for the synthesis of germanium nanostructures and organogermanium compounds. Mechanochemistry is also utilized for the synthesis of trisubstituted pnictides. Mechanochemical treatment of bromobenzene with either Na3Sb or Na3Bi allows for the formation of triphenylstibine or triphenylbismuthine, respectively. The synthesis of the alkali metals pnictide precursors is reported as well. The synthesis of triphenylstibine produces SbPh3 as the major product from the reaction. The synthesis of triphenylbismuthine produces more Wurtz-type coupling products, which are due to the BiPh3 acting as a catalyst. Tributyl and triphenyl analogues are reported as well. The trialkylated analogues for both Sb and Bi produce more Wurtz type coupling products. This would allow for a more cost effective and scalable, alternative methods than what is currently in use today

A series mixed metal supramolecular complexes were synthesized and studied by electrochemistry, photophysics and photochemistry. The complexes consisted of a single RuII or OsII polyazine light absorber bound to a cis-RhIIICl2 moiety through a polyazine bridging ligand. A related class of supramolecule is known to perform photoinitiated electron collection, photocatalysis of hydrogen from water, DNA photomodification and is known to kill mammalian cells; all with visible light irradiation. The complexes studied herein, [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3, [(bpy)2Ru(dpp)RhCl2(phen)](PF6)3, [(bpy)2Os(dpp)RhCl2(phen)](PF6)3, and [(tpy)OsCl(dpp)RhCl2(phen)](PF6)2 were synthesized in moderate yields (54-84%) by reaction of the appropriate monometallic visible light absorbing subunit with a slight excess of K[(phen)RhCl4]·3H2O (bpy = 2,2'-bipyridine, bpm = 2,2'-bipyrimidine, 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine, and tpy = 2,2':6',2"-terpyridine). Voltammetric analysis of [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3 revealed a reversible oxidation at 1.76 V (vs. Ag/AgCl) (RuIII/II). A reversible reduction at â 0.14 V (bpm0/-), and quasi-reversible reductions at â 0.77 V and â 0.91 V each corresponded to a one electron process, bpm0/â , RhIII/II and RhII/I. The electrochemistry of [(bpy)2Ru(dpp)RhCl2(phen)](PF6)3 showed a reversible oxidation at 1.61 V (RuIII/II), and quasi-reversible reductions at â 0.39 V, â 0.74 V and â 0.98 V. The first two reductive couples corresponded to two electrons, consistent with Rh reduction. [(bpy)2Os(dpp)RhCl2(phen)](PF6)3, and [(tpy)OsCl(dpp)RhCl2(phen)](PF6)2 each exhibited reductions similar to the dpp bridged Ru,Rh dyad, but with OsIII/II based oxidations at 1.24 V and 0.83 V, respectively. The complexes [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3 and [{(bpy)2Ru(bpm)}2RhCl2](PF6)5 display Ru(dπ)â bpm(π*) CT (MLCT) transitions at 581 nm and at 594 nm, respectively. The dpp bridged Ru,Rh bimetallic and Ru,Rh,Ru trimetallic display Ru(dπ)â dpp(π*) CT transitions at 509 nm and 518 nm, respectively. Similarly, [(bpy)2Os(dpp)RhCl2(phen)](PF6)3 absorbs strongly at 520 nm versus 534 nm for [{(bpy)2Os(dpp)}2RhCl2](PF6)5, both with low energy tails at 800 nm indicative of Os centered MLCT transitions. Overlapping Os(dπ)â dpp(π*) and Os(dπ)â tpy(π*) transitions occur at 536 nm with low energy tails at 856 nm for both [(tpy)OsCl(dpp)RhCl2(phen)](PF6)2 and [{(tpy)OsCl(dpp)}2RhCl2](PF6)3. Emission from [{(bpy)2Ru(dpp)}RhCl2](PF6)5 and [(bpy)2Ru(dpp)RhCl2(phen)](PF6)3 at room temperature and 77 K was red shifted and less intense than emission from [(bpy)2Ru(dpp)Ru(bpy)2](PF6)4, consistent with quenched emission from a Ru(dπ)â dpp(π*) 3MLCT state. Transient absorption spectroscopy supported assignment of the emissive state as Ru(dπ)â dpp(π*) CT in nature. The complexes [(bpy)Ru(dpp)RhCl2(phen)](PF6)3 (τ =18 ns) and [{(bpy)2Ru(dpp)}2RhCl2](PF6)5 (τ = 16 ns) each exhibit shorter lived 3MLCT states than the Ru,Ru dyad (τ = 125 ns) in acetonitrile consistent with favorable electron transfer to Rh(III) to generate a metal to metal charge transfer (3MMCT) state. The photochemistry of [{(bpy)2Ru(dpp)}2RhCl2]Cl5, [{(tpy)OsCl(dpp)}2RhCl2]Cl3, [(bpy)2Ru(dpp)RhCl2(phen)]Cl3, and [(tpy)OsCl(dpp)RhCl2(phen)]Cl2 with DNA was investigated using gel electrophoresis and selective precipitation of a DNA/metal complex adduct. An array of high intensity LEDs was designed, constructed and validated to accommodate these high throughput photochemical experiments with DNA. Each of the metal complexes is suggested to undergo photobinding with DNA as well as to photocleave DNA. A 3MMCT state or a thermally accessible Rh centered 3LF state each are proposed as leading to photobinding, while a 3MMCT state is thought to be involved in DNA photocleavage. / Ph. D.

A series of mixed-metal bimetallic complexes [(TL)2M(dpp)RhCl2(TL)]3 (M = Ru and Os, terminal ligands (TL) = phen, Ph2phen, Me2phen and bpy, terminal ligands (TL) = phen, bpy and Me2bpy ), which couple one Ru or Os polyazine light absorber (LA) to a cis-RhIIICl2 center through a dpp bridging ligand (BL), were synthesized using a building block method. These are related to previously studied trimetallic systems [{(TL)2M(dpp)2RhCl2]5+, but the bimetallics are synthetically more complex to prepare due to the tendency of RhIII halide starting materials to react with diimine ligands to form cis-[Rh(NN)2Cl2]+ motifs. The bimetallic complexes, [(phen)2Ru(dpp)RhCl2(bpy)]3+, [(phen)2Ru(dpp)RhCl2(phen)]3+, [(Ph2phen)2Ru(dpp)RhCl2(phen)]3+, [(Me2phen)2Ru(dpp)RhCl2(phen)]3+, [(bpy)2Ru(dpp)RhCl2(bpy)]3+, [(bpy)2Ru(dpp)RhCl2(Me2bpy)]3+ and [(bpy)2Os(dpp)RhCl2(phen)]3+, were characterized and studied by electrochemistry, electronic absorption spectroscopy, ESI-mass spectrometry, steady-state and time-resolved emission spectroscopy. Ï¿" ï¿" The electrochemical properties of bimetallic complexes with polyazine ligands exhibit a reversible one-electron metal-based oxidation, a quasi-reversible RhIII/IICl2 overlapped with a small amount of RhII/ICl and an irreversible RhII/ICl2 �reductions prior to the reversible bridging ligand dpp0/- �reduction. ï¿" ï¿" The title bimetallic complexes are efficient light absorbers due to the [(TL)2MII(dpp)] light absorber subunit. The bimetallics display ligand-based ï¿"'ï¿"* transitions in the UV region and metal-to-ligand charge transfer (MLCT) transitions in the visible region of the spectrum with approximately half the absorption extinction coefficient values relative to the trimetallics in the spectrum. The Os,Rh bimetallic complex, [(bpy)2Os(dpp)RhCl2(phen)]3+, displays Os(dï¿")'dpp(ï¿"*) CT transition at 521 nm and a low energy absorption band at 750 nm in the near-infrared region representing direct 1GS'3MLCT excitation due to the high degree of spin orbital coupling in Os complexes. The bimetallic complexes [(phen)2Ru(dpp)RhCl2(bpy)]3+, [(phen)2Ru(dpp)RhCl2(phen)]3+, [(Ph2phen)2Ru(dpp)RhCl2(phen)]3+, [(Me2phen)2Ru(dpp)RhCl2(phen)]3+, [(bpy)2Ru(dpp)RhCl2(bpy)]3+ and [(bpy)2Ru(dpp)RhCl2(Me2bpy)]3+ display Ru(dï¿")'dpp(ï¿"*) MLCT transitions centered at 505, 508, 515, 516, 510 and 506 nm, respectively. The bimetallic complex [(Ph2phen)2Ru(dpp)RhCl2(phen)]3+ displays enhanced absorption. Ï¿" ï¿" The photophysical properties of Ru,Rh bimetallic complexes are close to those of trimetallic analogues. In room temperature acetonitrile, both bimetallic and trimetallic complexes display a weak and short-lived emission from the Ru(dï¿")'dpp(ï¿"*) 3MLCT excited state. For example, the bimetallic complex [(phen)2Ru(dpp)RhCl2(bpy)]3+ emits at 766 nm and the trimetallic complex [{(phen)2Ru(dpp)}2RhCl2]5+ emits at 760 nm. At 77 K in 4:1 ethanol/methanol glass, the bimetallics, as well as trimetallics, exhibit a more intense blue-shifted emission with a longer lifetime, which is from the same 3MLCT excited state. At 77 K, the low temperature emission from the same 3MLCT state of [{(phen)2Ru(dpp)}2RhCl2]5+ blue-shifts to 706 nm with the emission lifetime of 1.8 ms and the bimetallic [(phen)2Ru(dpp)RhCl2(bpy)]3+ emits at 706 nm (t = 1.8 ms). The Ru,Rh complexes 3MLCT excited states can populate Ru(dï¿")'Rh(ds*) triplet metal-to-metal charge transfer (3MMCT) excited states through intramolecular electron transfer at room temperature, which is impeded in the rigid matrice at 77 K due to the large reorganizational energy and restricted molecular motion. The emission of Os,Rh bimetallic complex [(bpy)2Os(dpp)RhCl2(phen)]3+ could not be detected by our instruments likely due to its expected red-shifted emission which lies outside our detector window. ï¿" ï¿" �The Ru,Rh bimetallics display interesting and efficient photo-reactivity with DNA activated by visible light. The DNA gel shift assay, selective precipitation, ESI-mass spectrometry and polymerase chain reaction (PCR) studies suggest that Ru,Rh bimetallic complexes photobind to DNA following visible light excitation. This reactivity is not observed for analogous Ru,Rh,Ru trimetallics due to the steric protection of the Rh site in that motif. The bimetallic [(TL)2Ru(dpp)RhCl2(TL)]3+ systems can photobind and photocleave DNA through low-lying 3MMCT excited states when excited by the low energy visible light, with or without molecular oxygen. This is unusual but desirable reactivity for photodynamic therapy (PDT) drug development. The Os,Rh bimetallic complex [(bpy)2Os(dpp)RhCl2(phen)]3+ photobinds and photocleaves DNA under red therapeutic light excitation without molecular oxygen, an unprecedented result. Polymerase chain reaction experiments were used to evaluate the impact on DNA amplification of the DNA photo-modification and photo-damage induced by [(bpy)2Os(dpp)RhCl2(phen)]3+ under red light irradiation. Either photobinding or photocleavage induced by red light excitation of [(bpy)2Os(dpp)RhCl2(phen)]3+ on DNA inhibits amplification via PCR methods, a model for in vivo replication. Moreover, significant thermal stability of DNA photo-modification over 90 "C is required for PCR. A red light-activated drug that acts in an oxygen-independent mechanism to impede DNA amplification is unique in this field and desirable for study as a new class of PDT drugs. / Ph. D.